Admin Toolbar Extra Tools Confirmations
This module adds a JavaScript confirmation prompt before clearing caches, preventing accidental cache flushes on production sites.
A simple extension to the Admin Toolbar Extra Tools module that's part of the Admin Toolbar project that shows a javascript confirmation dialog when clicking links relating to flushing caches, but only when on a production site.
Post-Installation
This should 'just work' but if the module needs help identifying your site's production and non-production environments, then have a look at the code in admin_toolbar_tools_confirm_is_likely_production_site and maybe think about setting the admin_toolbar_tools_confirm.production_site setting in settings.php.
Project genesis
The idea for this module came from this issue: #3567243: Feature idea: optional confirmation form for flushing caches